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acadiel

Thermal printer DSR Hacking help wanted

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52 minutes ago, Tursi said:

It looks like it's setting the CRU timer to the maximum possible value - maybe initializing a timeout?

 

Not sure why zero CRU bit 3... zeroing bit 0 is probably just to ensure a known starting state. The LDCR will switch to timer mode when bit 0 gets a 1, and then next 14 bits will fill the timer register. The last SBZ exits timer mode and starts counting.

 

Edit: ah, bit 3 is the timer interrupt bit

 

 

The timer generates interrupt 3. SBZ 3 disables INT3.

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On what I call the "data" side of the Thermal printer PCB are:

 

U10 SN74LS126AN - "QUADRUPLE BUS BUFFERS WITH 3-STATE OUTPUTS"

U11 SN74LS244N - "Octal Buffers And Line Drivers With 3-State Outputs"

U12 CN36006N 8116 S 1501709-2 - 4K DSR ROM

U13 SN7407N - "HEX BUFFER DRIVER"

U14/U15 2x SN74LS138 - "3 LINE TO 8-LINE DECODER/DEMULTIPLEXER"

 

The Thermal Printer side of the circuit has:

U1/U2/U3 - ULN2003AN - High Voltage, High Current, Darlington Transistor Arrays

U4/U5/U6/U7 4X SN74LS259N - "8 Bit Addressable Latch"

U8 SN74LS (can't read - maybe 122?)

U9 74LS02N - Quadrupule 2-input positive NOR gates

 

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On 4/14/2020 at 3:12 PM, acadiel said:

Not that I see.  It's just a bunch of logic chips and a 4K DSR ROM (I'm thinking it's a 2532 pinout if I'm not mistaken, so I need to get a 2764 to 2532 adapter.)

 

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

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2 minutes ago, InsaneMultitasker said:

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

 

I'm going to socket it this weekend and try a 2532 and see if it works.  :)

 

I can only guess - nobody has ever found any schematics or service manual for the TP.  :(

 

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3 minutes ago, mizapf said:

Disassembling a mere 2K should be a rather simple job.

I disassembled and commented a good portion of it.  See post #22 if you'd like to gnaw on it for a while.

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Tempting...

(Actually, while doing all that emulation work, a surprising amount of work piled up behind my back...)

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3 hours ago, InsaneMultitasker said:

When I disassembled the 8K ROM image, I noticed that the DSR is only 2K.  And it is pretty well crammed into that 2k window... did TI produce a 2K ROM?  My thought was they created the DSR with 2K in mind but used 4K hardware?

 

Do you mean, did they sell 2K ROM chips? The TMS4800 is a 2Kx8 mask ROM . According to the 1975 data book, you would deliver your ROM content on punch-cards, encoded in octal digits. By 1984 the low end was the 4732 ROM. The 2516 2Kx8 EPROMs were sometime in between.

 

1975   https://archive.org/details/bitsavers_tidataBookorMemoryDataBook_9924035/page/n111/mode/2up/search/2k

1984   https://archive.org/details/bitsavers_tidataBook984_15352413/page/n11/mode/2up

 

 

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On 4/13/2020 at 7:33 PM, Tursi said:

If you can, give this a try. It looks like the ROM is only 4k, so you may need a 4k EPROM instead of 8k.

 

There seem to be only two places that verify the record length. I changed them to pull the record length from >4001 - so the second byte of the ROM, and set this one to >1E (ie: 30).

 

Beyond that, I can only say it doesn't crash. Classic99 doesn't emulate the hardware of the Thermal Printer nor do I know how it works, so I can't check it formatted the output correctly. But it loads the PAB and then times out gracefully. If the PAB is right, based on what I see above, good chance the rest will be. ;)

TIThermalMod.zip 2.17 kB · 9 downloads

 

The thermal printer mod appears to work when printing a 40 character line from BASIC.  A-Maze-ing also works!

 

 

EAE5A157-E5D0-4AAD-A120-B11CD8B5CE9A.jpeg

60C6D400-A174-4FCB-B674-9047AF03BC43.jpeg

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48 minutes ago, OLD CS1 said:

Never knew A-Maze-Ing did that...

I was thinking the same thing. I'm a-maze-d.

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9 hours ago, acadiel said:

The thermal printer mod appears to work when printing a 40 character line from BASIC.  A-Maze-ing also works!

 

 

 

60C6D400-A174-4FCB-B674-9047AF03BC43.jpeg

I love this. A*Maze*Ing was my first module.  I can just imagine another childhood containing these tiny printed mazes. (How about a Complex maze?)

Thanks!

 

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12 hours ago, FarmerPotato said:

I love this. A*Maze*Ing was my first module.  I can just imagine another childhood containing these tiny printed mazes. (How about a Complex maze?)

Thanks!

 

An older test I did with narrower paper...

B6B1ED5B-16FD-4569-B573-BB3883DA725A.jpeg

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